Sand the shrink plastic lightly to prepare it – first in a horizontal direction and then vertical. We used very fine sandpaper.Punch a circle out of the plastic, about double the size of the button you want to make (the plastic shrinks by about half when it is baked).Stick the circle with the roughened side facing upwards over the picture that you want to use for the design for your button. We used sheet music. Trace the design onto the plastic with your marking pen.Punch the buttonholes: First punch out a paper circle in the same size, fold it in quarters and then unfold the last fold. Punch a hole in the middle of the foldline. Open up the circle completely - you now have a template for the buttonholes.Place the plastic circle on the piece of cardboard and bake it for 3-5 minutes in an oven preheated to 170°C. NOTE Do not place the plastic directly onto a baking tray.The plastic will start to shrink and will contort and twist in the oven. Leave it in the oven until it lies flat again and has shrunk by half. Remove and leave to cool.